Success in the development of high-quality and ultra-wideband radio frequency (RF) sources has led to the exploration of applications of such technology, such as ultra-wideband phased-antenna arrays. An example of this may be found in G. J. Schneider et al., “Optical Generation of Narrow-Line RF by Injection Locking of Modulated DFB Lasers” CLEO Conference, 2011, incorporated herein by reference. In a proposed approach of this paper, two laser outputs having a frequency difference corresponding to a frequency of an RF signal may be fed into an optical interleaving and feeding network consisting of two 1-to-N beam splitters, N electro-optic phase modulators, N2-to-1 beam combiners and fiber couplers. The beam splitting, phasing, and recombining can be achieved through typical fiber-based components.
The proposed approach, however, imposes some technical difficulties in the practical implementation. Due to thermal and mechanical stresses in each channel, the relative phases between channels may drift over time, thereby resulting in significant distortion in RF beamforming.